Electron discharge device



Nov. 20, 1962 E. F. REXER. JR

ELECTRON DISCHARGE DEVICE Filed Aug. 2'7, 1956 INVENTOR. EDWARD F. REXER JR. /4M% I-rif Lu.

3,065,291 ELECTRDN DiStlHARGE DEVlQE Edward F. Rexer, In, Hopkins, Minn, assignor to Minneapolis-Honeywell Regulator Company, Minneapoiis, lViinrL, a corporation of Delaware Filed Aug. 27, 1956, Ser. No. 606,325 2 Claims. (Ci. 174-5964) The present invention relates to ceramic electron tubes, and especially to improved methods of bringing the terminal connections of such a device through the tube envelope.

An object of this development is to provide an electron discharge device having a ceramic envelope comprising two sections sealed together, and in which a number of the necessary lead-in terminals are brought through the single seal, thereby reducing to a minimum the number of vacuum tight seals required in the envelope.

A more specific object of this invention is to provide an electron discharge device having a ceramic envelope comprising a ceramic base portion and a cylindrical ceramic upper portion, in which radial metallic conductors are metalized onto said ceramic base to provide a plurality of lead-in conductors through the single sealing area between said base and upper ceramic member.

This and other objects of my invention will be understood upon consideration of the accompanying specification, claims, and drawing of which:

FIGURE 1 is a top plan view of the interior of the envelope showing an embodiment of my invention;

FIGURE 2 is a cross section view of the tube from points 11 of FIGURE 1;

FIGURE 3 is a perspective view of the tube; and

FIGURE 4 is a detailed view of the seal and metalized conductive member.

Referring now to FIGURE 1 of the drawing, which is a top view and partial cross-sectional, the cross-section being taken from points 11 of FIGURE 2, there is shown a ceramic base member and a cylindrical ceramic upper portion 11. The ceramic envelope may be of any suitable nonporous ceramic type material such as the alumina type ceramics commercially available. A number of metal pins 12 through 20 are fastened to the base member 10, and stand upright therefrom to support the internal components of the tube, not described in detail. These pins are also shown in FIGURES 2 and 3. In FIGURE 2 the cross-section of pin 12 shows that it may be secured into a depression of the base member 10 by means of a soldering technique, or the like. It is obvious that the pins may be fastened in any other suitable manner, if desired.

The base section lilof the ceramic envelope has a main portion substantially in the shape of a disc, and a cylindrical lip 30 around the edge of the base member is made to mate with and be sealed to the upper section of the envelope 11.

In FIGURE 3, extending radially across the lip area 30 of the ceramic base there is shown a plurality of conductive paths 31. These conductive paths are preferably a metalizing material applied to the base ceramic in strips, extending radially from the pins 12 and 20 inclusive and across the final seal area to terminals on the exterior of the tube. In one successful embodiment of the invention a metalizing mixture of molybdenum and manganese was painted on the ceramic base It and subsequently sintered or fired at an elevated temperature. A silver paste or Patented Nov. 20, 1962 ice other suitable metalizing mixture may also be utilized to provide the conductors. It will be appreciated that the metalized conductor is very thin, preferably of a thickness in the order of one mil. It will be obvious that this sintering, in order to insure a hermetic or vacuum seal, must involve bringing the metalized strips up to the melting temperature of at least the lowest melting point material of the strips. It will furthermore be obvious that in order to avoid interruption of the electrical continuity of the very thin strips, the sintering must occur at a temperature below the melting point of the ceramic since otherwise the material of the strips would tend to disperse into the soft ceramic. The obvious advantage of this invention is that the number of seals in the tube envelope is reduced to a minimum.

In order to prevent electrical leakage between the plurality of conductors, a nonconductive sealing material 32 is used to bond together the upper ceramic section to the ceramic base of the tube. Any suitable nonconductive sealing material which will bond ceramic to ceramic and ceramic to metal can be used, however, a glass frit is preferred. The sealing material 32 may be applied to the final seal areas of the two envelope sections, and the seal is perfected by a temperature cycle sufiiciently high to melt the glass frit. The temperature cycle used to accomplish the final seal is substantially lower than the melting point of the metalizing material so that the conductivity of the metalized strips are not effected. Since, as pointed out above, the melting or sintering temperature of the metalized strips must be below the melting point of the ceramic, it will be obvious that the melting point of the glass frit must be relatively low as compared with the melting point of the ceramic. In one specific embodiment of this invention a well known type glass frit was used, which contained silicon dioxide, calcium carbonate, and boron oxide.

FIGURE 4 shows a more detailed view of the metalized conductor 31 on the base 10 and of the glass frit seal 32. An obvious modification, that may be employed if desired, is to utilize thin metallic strips through the seal area in which the nonconductive sealing material surrounds the conductive strip.

In general, while I have shown certain specific embodiments of my invention, it is to be understood that this is for the purpose of illustration and that my invention is to be limited solely by the scope of the appended claims.

I claim:

1. An electron discharge device comprising an envelope having upper and lower sections of ceramic, a nonmetallic nonconductive bond uniting said upper and lower sections of ceramic, a plurality of electrodes within said element supported from said lower section, a plurality of terminals on the exterior of said envelope, and a plurality of wide and thin conductive strips metalized onto the surface of said lower section and extending radially from the interior of said envelope where each strip is connected to a separate electrode and across the single seal area of said lower section to the exterior terminals.

2. An electronic valve comprising an envelope having upper and lower sections of ceramic, each section having a sealing edge to be sealed together; a plurality of electrodes mounted within said envelope; a non-metallic non-conductive bond uniting together said upper and lower sections of ceramic to form a vacuum tight envelope; and a plurality of relatively wide metallic conductive strips metalized to the surface of one of said envelope sections, References Qited in the file of this patent each strip being electrically connected to a separate one of UNITED STATES PATENTS said electrodes, said stri s extendin radiall from the interior of said envelope and across said sealing edge of g i s 1936 aier et a1. Aug. 22, 1939 said sectlon to the exterior of said envelope, said con- 5 2173 906 Katsch Sept 26 1939 ductive strips being relatively thin with respect to said 2:210i131 gggf:::::::: g 194.0 bond, said envelope portions thus providing a vacuum 2,269,073 Zinke Jam 6, 71942 tight envelope having an electrical path from each elec- 2 277 423 W i h M 24 1942 trode to the exterior of said envelope through the single m 2,731,578 McCullough J an. 17, 1956 seal area. 2,736,835 Van Tol Feb. 28, 1956 

